1. Field of the Invention
The present invention relates to an apparatus and method for operating a DVD player, and more particularly, to an offset setting apparatus and method for separately setting and adjusting an offset in a DVD player during an initial reproducing operation of the DVD player, and an offset adjusting apparatus and method for adjusting an offset in a DVD player.
2. Description of the Related Art
In general, a DVD player is an apparatus for reproducing information recorded on various types of optical discs, such as compact discs (CDs), read-only memory compact discs (CD-ROMs), laser discs (LDs), mini discs (MDs), and digital video discs (DVDs).
Adjustment of an offset is carried out during the initial reproducing operation of a DVD player. The initial reproducing operation of a DVD player refers to operations of the DVD player that are performed after an optical disc is inserted into the DVD player and before information recorded on the disc is displayed. During the initial reproducing operation, adjustment of an offset is performed. A method of adjusting an offset in a disc player is disclosed in U.S. Pat. No. 6,252,835.
FIG. 1 is a flowchart illustrating a conventional method of adjusting an offset in a DVD player. In the conventional method, when a DVD player begins the initial reproducing operations, an ABCD offset value is adjusted in operation 100. More specifically, in operation 100, a previously set reference ABCD offset value is replaced with an ABCD sum signal value, which represents a voltage value, output from a photo detector (not shown) in an optical pickup (not shown).
After the adjustment of the ABCD offset value, a focus offset is adjusted in operation 101. That is, a previously set reference focus offset value is updated with a variable of the position of a focus lens, in response to a focus error signal which is detected by the photo detector, calculated, and output.
After operation 101, a constant linear velocity (CLV) of an optical disc is adjusted in operation 102.
After the CLV adjustment, a deviation in the optical disc to be reproduced is adjusted for in operation 103. In general, an optical disc is subject to wear and tear resulting in flaws such as, for example, black dots or scratches. If an optical disc has such flaws, a signal output from the disc may be erroneously read out. If the data is erroneously read out, data recorded on the disc cannot be accurately reproduced. Therefore, in operation 103, flaws of the optical disc are detected and deviations such as eccentricity or deflection are compensated for.
After the deviation adjustment, data to be reproduced is searched for in operation 104 and then reproduced in operation 105.
Conventionally, during the initial reproducing operation of a DVD player, an offset in the DVD player is adjusted by the method illustrated in FIG. 1. However, this method is disadvantageous in that physical impacts or electrical shocks make it difficult to obtain a correct focus/CLV/track error value during reproducing operations of the DVD player. As a result, an offset in a DVD player may be adjusted using incorrect data, thereby causing poor performance of the DVD player.